3D printed thread and bolt generator
Generate a bolt/screw and its matching nut from a standard thread designation (M3, M8, 1/4-20…)
A bolt or screw and the nut that threads onto it, both derived from one designation — picking M8 sets the 1.25 mm pitch from the ISO table, and a thread at the wrong pitch mates with nothing while looking perfectly correct on screen. The heads follow the standards too: ISO 4032 hex, 4762 socket cap, 7380 button, 7046 countersunk. The first turn is chamfered so it starts straight instead of cross-threading. Download a print-ready STL or 3MF.
How the 3D printed thread and bolt generator works
What you can adjust
- Size — M2 — Ø2 × 0.4 mm · M2.5 — Ø2.5 × 0.45 mm · M3 — Ø3 × 0.5 mm · M4 — Ø4 × 0.7 mm
- Thread length — 2–200 mm
- Head — Socket cap · Hex · Countersunk (flat) · Button (dome)
- Also generate the matching nut
- Fit — Tight · Normal · Loose · Custom
- Thread clearance — 0–2 mm
Metric thread pitch chart
ISO coarse pitches from M1.6 to M48, with the tap drill (diameter minus pitch, the shop rule). The generator makes bolts and nuts from M2 to M8; the Thread shape covers the whole chart.
| Size | Pitch | Tap drill (D − P) |
|---|---|---|
| M1.6 | 0.35 mm | 1.25 mm |
| M2 | 0.4 mm | 1.6 mm |
| M2.5 | 0.45 mm | 2.05 mm |
| M3 | 0.5 mm | 2.5 mm |
| M3.5 | 0.6 mm | 2.9 mm |
| M4 | 0.7 mm | 3.3 mm |
| M5 | 0.8 mm | 4.2 mm |
| M6 | 1 mm | 5 mm |
| M8 | 1.25 mm | 6.75 mm |
| M10 | 1.5 mm | 8.5 mm |
| M12 | 1.75 mm | 10.25 mm |
| M14 | 2 mm | 12 mm |
| M16 | 2 mm | 14 mm |
| M18 | 2.5 mm | 15.5 mm |
| M20 | 2.5 mm | 17.5 mm |
| M22 | 2.5 mm | 19.5 mm |
| M24 | 3 mm | 21 mm |
| M27 | 3 mm | 24 mm |
| M30 | 3.5 mm | 26.5 mm |
| M36 | 4 mm | 32 mm |
| M42 | 4.5 mm | 37.5 mm |
| M48 | 5 mm | 43 mm |
Metric screw and nut dimensions
What the generator sizes from the designation: clearance holes to ISO 273, nuts to ISO 4032 and socket heads to ISO 4762. Heat-set insert pockets are for typical tapered brass inserts, and vary by brand.
| Size | Pitch | Clearance hole | Close hole | Hex nut (across flats × thick) | Socket head (Ø × height) | Heat-set insert (Ø × depth) |
|---|---|---|---|---|---|---|
| M2 | 0.4 mm | 2.4 mm | 2.2 mm | 4 × 1.6 mm | Ø3.8 × 2 mm | Ø3.2 × 4 mm |
| M2.5 | 0.45 mm | 2.9 mm | 2.7 mm | 5 × 2 mm | Ø4.5 × 2.5 mm | Ø3.5 × 4 mm |
| M3 | 0.5 mm | 3.4 mm | 3.2 mm | 5.5 × 2.4 mm | Ø5.5 × 3 mm | Ø4 × 5.7 mm |
| M4 | 0.7 mm | 4.5 mm | 4.3 mm | 7 × 3.2 mm | Ø7 × 4 mm | Ø5.6 × 7.6 mm |
| M5 | 0.8 mm | 5.5 mm | 5.3 mm | 8 × 4.7 mm | Ø8.5 × 5 mm | Ø6.4 × 9.5 mm |
| M6 | 1 mm | 6.6 mm | 6.4 mm | 10 × 5.2 mm | Ø10 × 6 mm | Ø8 × 12.7 mm |
| M8 | 1.25 mm | 9 mm | 8.4 mm | 13 × 6.8 mm | Ø13 × 8 mm | Ø9.6 × 12.7 mm |
Printing threads that turn
- Pick the size, not the pitch. Choosing M8 sets the 1.25 mm pitch from the ISO table. A thread at the wrong pitch mates with nothing, while looking perfectly correct on screen.
- The nut already has clearance. The nut is tapped by subtracting the internal form of the same designation, which already carries the radial clearance a printed pair needs. Fit (Tight, Normal, Loose) changes it; under Custom, Thread clearance is the diametral figure.
- The first turn is chamfered. A thread that ends in a square face catches and cross-threads as you start it; a 45° lead-in guides it in straight.
- Choose the orientation. Stood on its head, every turn prints round and the thread comes out cleanest, but the shank is weakest across its layers. Laid on its side it is stronger, and the face on the bed prints flat.
- Small threads are hard. A pitch of 0.5 mm or finer (M3 and down) is close to the width of one extrusion line, so expect a rough fit. At that size a heat-set insert or a bought screw is often the better part.
Thread questions
Can you 3D print threads that work?
Yes. This generator makes the bolt and its nut from one ISO designation, so they mate with each other and with real hardware. The nut carries clearance and the first turn is chamfered so it does not cross-thread.
What is the pitch of an M8 thread?
1.25 mm for ISO coarse, with a 6.75 mm tap drill. The chart above has the rest.
What size hole does a heat-set insert need?
For M3, a Ø4 × 5.7 mm pocket with typical tapered brass inserts. Brands vary, so check your inserts’ data sheet.
Which head should I choose?
Socket cap and Hex are tightened with a tool. Countersunk (flat) sits flush. Button (dome) gives the same bearing face in less height. Thumb screw is for hand-tightening: its knob is sized from the thread, not looked up in a standard.